Coolant filter manufacture and composition for use in same

ABSTRACT

In a method for manufacturing a circulating coolant system filter which includes assembling a filter medium and a filter canister into which a supplemental coolant additive can be placed to provide at least one beneficial property to the circulating coolant, the improvement comprising: automatically introducing the supplemental coolant additive into the filter canister in the form of a liquid-powdered solids slurry.

This application is a continuation-in-part of co-pending applicationSer. No. 904,485, filed Sept. 9, 1986 now abandoned.

This invention relates to an improved method for manufacturing acirculating coolant system filter and to a composition useful in suchimproved method. More particularly, the invention relates tomanufacturing such a filter which includes a filter medium and a spacefor a supplemental additive package to improve the properties of thecirculating coolant.

Coolants are often needed in industry, e.g., in stationary and vehicularengines, to maintain the system temperature suitable for effectiveoperation. Frequently, such coolants, often liquid coolants, circulateover a long period of time through the system, e.g., internal combustionengines such as diesel engines, spark ignited engines and the like, thetemperature of which is to be maintained. Such long term use ofteninvolves substantially continuous filtering of the coolant to removepotentially harmful solid particles from the circulating system. Also,such long term use often requires that the coolant be fortified with asupplemental coolant additive which is added to the coolant to impartone or more beneficial properties, e.g., added corrosion inhibition,anti-foaming characteristics, etc., to the circulating coolant. Variousadditive compositions are disclosed in the following U.S. Pat. Nos.:3,231,501; 3,962,109; 4,242,214; 4,455,248; 4,564,465; 4,587,028; and4,588,513 each of which is incorporated in its entirety herein byreference.

Such supplemental coolant additive (SCA) may be added directly to thecoolant in the form of a concentrated aqueous solution of the activecomponents of the SCA. For example, diesel truck drivers may beinstructed to periodically add defined amounts of such solutions to thecooling system of their rigs. In certain systems, a solid SCA isincluded in a circulating coolant filter. See, for example, U.S. Pat.No. 3,645,402 which teaches a disposable-type filter for an internalcombustion engine having a canister containing a corrosion inhibitor ina pallet preferably spun onto an adapter.

Using the filter to provide the SCA to the circulating coolant hassubstantial advantages over using concentrated SCA solutions. Forexample, quality control of the manufacture of the SCA/filtercombinations insures that each filter has the proper amount of SCA sothat the proper dosage of SCA is added to the circulating coolant.

However, manufacturing such solid SCA/filter combinations has someserious drawbacks. For example, solid SCA powders or pellets of solidSCA are inserted into the filter canister by hand. This is not only timeconsuming, labor intensive and costly, but it also may expose workers topotentially dangerous materials often included in the SCA. Suchmaterials include, for example, tetraborates, alkali metal nitrites,alkali metal phosphates, heavy metals such as molybdenum, and the like.Also, the pellets must be formed in a variety of sizes to fit thevarious sizes of filter canisters employed. This pelleting, and inparticular producing various sized pellets, is a costly operation.Pre-formed pellets often pick-up moisture from the atmosphere and swellto the point where they do not fit into the filter canister and must bediscarded or reprocessed. This again is costly. In addition, care mustbe exercised to avoid any active components, e.g., liquids, which renderthe SCA unpelletizable. A somewhat comparable compounding limitationexists with the above-noted concentrated solutions of SCA. In thisinstance, only active components which are soluble in the solvent of theconcentrated solution of SCA are used. These compounding limitationstend to detrimentally affect the effectiveness and/or cost of the SCA.Clearly, an improved method of manufacturing SCA/filter combinations forcirculating coolant systems would be advantageous.

Therefore, one object of the present invention is to provide an improvedmethod for manufacturing a circulating coolant system filter.

Another object of the invention is to provide a composition useful inthe manufacture of a circulating coolant system filter. Other objectsand advantages of the present invention will become apparenthereinafter.

An improved method for manufacturing a circulating coolant system filterhas been discovered. Such filters include a filter medium and a spaceinto which a supplemental coolant additive can be placed to provide atleast one beneficial property to the circulating coolant. The presentimprovement comprises introducing, preferably automatically introducing,the supplemental coolant additive into the space in the form of aliquid-powdered solids slurry. As used herein, the term "automatically"refers to introducing the slurry in a substantially totally mechanizedmanner which can be achieved substantially without any human beingcoming in contact with the slurry.

The present invention provides substantial advantages. For example, onlyone slurry is needed even if different sized filters are to bemanufactured. In contrast, different sized solid pellets of SCA areoften required to be produced for each size of filter. The slurry can beblended, shipped and stored in bulk. The slurry can be introduced intothe filter space, e.g., filter canister, automatically by conventionalmeans, such as automatic injectors and pumps. Such means can be presetto deliver the desired amount of slurry to each filter. In this manner,the amount of slurry introduced can be varied depending on the size andSCA requirements of the filter being manufactured. Such automaticintroduction also reduces the exposure and physical contact of thefilter manufacturing workers with the SCA, which may include one or morepotentially dangerous (to human beings) components.

Substantial economies in producing the present slurries are alsoobtained. For example, the questions of solubility in a carrier solventand pelletizibility are no longer factors in making up the SCA.Components which are not soluble in the liquid phase of the slurry orwhich are not pelletizible may be used in the presently useful SCAslurries. This provides substantial blending flexibility and potentialcost reductions. To illustrate, less expensive raw materials, such assodium salts in place of potassium salts, may be employed since carriersolubility is not a factor in the blending of the slurry.

The SCA used in the present slurries often comprises a combination ofcomponents each of which acts to provide a least one beneficial propertyto the circulating coolant. For example, such SCA's often include atleast one corrosion inhibitor, preferably a plurality of corrosioninhibitors, to inhibit the propensity of the circulating coolant tocause corrosion in one or more parts of the system being cooled by thecoolant. More than one corrosion inhibitor is preferably included in theSCA to inhibit different types of corrosion and/or to inhibit corrosionof different materials of construction, e.g., different metals, makingup the system, e.g., internal combustion engine, being cooled by thecoolant. For example, a single engine may include a number of metals,such as copper, solder, brass, steel, cast iron, and cast aluminum,which are exposed to the coolant and which may require different SCAcomponents to inhibit corrosion. The SCA may include one or more otheractive components, such as detergents, cleaners, chelating agents,anti-foaming agents, freezing point depressants, dyes, dye tracers andthe like. Many individual SCA components and SCA blends are conventionaland well known in the art and/or are commercially available. As known byone skilled in the art, care should be exercised to avoid includingcomponents in the same SCA which unduly interfere with the overallfunctioning of the SCA and/or which will react together to formundesirable compounds. For example, one should avoid combining nitrileswith amines to avoid formation of nitrosamines, which are a potentialhealth hazard.

Many of the patents listed above and incorporated by reference hereinprovide examples of SCA's useful in the present invention. Withoutlimiting the scope of the present invention, included among the usefulSCA components are alkali metal phosphates, nitrates, nitrites,molybdates, silicates, mono- and di-carboxylates, sulfonates,polyacrylates, and the like; mercaptobenzotriazole, tolytriazole, andthe like; and defoamers, dyes, fluorescent agents (dye tractors) and thelike. One particularly preferred SCA is sold by Fleetguard, Inc. underthe tradename DCA IV.

The liquid phase of the present liquid-solid slurry may be any suitablematerial which is substantially compatible with the remainder of theslurry, the remainder of the filter, the circulating coolant and thesystem to be cooled. The liquid phase need not include any of the SCA.However, it is preferred that at least a portion of at least one of theactive components, e.g., corrosion inhibitors, of the SCA be present,e.g., solubilized, in the liquid phase of the slurry. The solids of theslurry also preferably include at least a portion of one of the activecomponents, e.g., corrosion inhibitors, of the SCA. In one embodiment,the liquid phase comprises at least one freezing point depressant forthe circulating coolant. For example, when the circulating coolant isaqueous based, for example, a mixture comprising water and ethyleneglycol, the liquid phase of the slurry can, and preferably does,comprise ethylene glycol. In one embodiment, a major amount of theliquid in the slurry is ethylene glycol. Although the amount of ethyleneglycol in the slurry is often not sufficient to depress the freezingpoint of the circulating coolant to the full extent desired, suchethylene glycol does depress the coolant's freezing point at least to alimited degree. More importantly, ethylene glycol in the slurry has beenfound to be compatible with a substantial number of SCA components, withthe aqueous based coolant and with the systems that are normally cooledwith such coolants.

The slurry may include a water-based liquid phase. However, it has beenfound that in slurries which contain non-aqueous liquid components thepresence of substantial amounts of liquid water may lead to increaseddetrimental separation between the solids and liquid phases of theslurry. Preferably, the slurry includes less than about 15%, morepreferably less than about 5%, by weight of liquid water. Particularlygood results are obtained with slurries which are substantiallynon-aqueous, i.e., contain substantially no liquid water.

The slurry may further comprise one or more additive components in anamount effective to provide one or more beneficial properties to theslurry. For example, the slurry may contain a suspension agent, such ascellulose derivatives, other polymeric suspension agents and the like,to improve the uniformity and/or stability of the slurry and to reducesolid-liquid separation. Such suspension agents tend to increase theshelve life of the present slurries. However, it is preferred tointroduce the slurry into the filter within about 2 months, morepreferably within about 1 month and still more preferably within about 2weeks, of the time the slurry is first formed to avoid unduedeterioration of the slurry. The slurry is preferably substantiallyuniform when it is introduced into the filter. Typically, little or noagitation of the slurry is required prior to placing the slurry in thefilter if such placing is performed within the times listed above. Ofcourse, slurry agitation just prior to the slurry being introduced intothe filter may be useful in any event to insure the manufacture of aquality, substantially uniform product.

The present slurries are preferably compounded of componentssubstantially dispersible or soluble in the circulating coolant.

The relative amounts of solids and liquid in the present slurries mayvary over a wide range depending, for example, on the nature of thesolids and liquid being employed and the slurry properties desired. Inorder to maximize to effective amount of SCA per unit volume of slurry,it is preferred that the slurry contain less than about 50%, morepreferably about 5% to about 40%, by weight of liquid; and more thanabout 50%, more preferably about 60% to about 95%, by weight of solids.An especially useful slurry contains about 10% by weight of liquid andabout 90% by weight of solids.

The powdered solids useful in the present slurries have particle sizessubstantially smaller than the pellets of SCA used in certain previousfilter canisters. A major amount by weight, i.e., at least about 50% byweight, of the solids in the slurry have a maximum transverse dimension,i.e. diameter, of less than about 500 microns. More preferably,substantially all of the solids in the slurry are present in particleshaving diameters of less than about 250 microns.

The present slurries can be prepared by periodically over time addingrelatively small increments of the desired powdered solids to thedesired liquid. Alternately, substantially continuous addition of thesolids to the liquid may be employed. This addition is accompanied bymixing, e.g., using a mechanical mixer, to provide a substantiallyuniform blend. The addition continues until the desired composition isobtained.

After the desired amount of slurry is introduced into the filter, theslurry may separate into liquid and solid phases, or may form asubstantially solid mass. In any event the SCA/filter combination may bestored for a substantial period of time prior to use with little or nodetrimental effect on the SCA.

The SCA/filter combination may be used by placing it in fluidcommunication with the circulating coolant. Such filter combinations aredisclosed in U.S. Pat. No. 3,645,402 which is incorporated herein in itsentirety by reference. In any event, once such fluid communication isestablished, the SCA preferably disperses or solubilizes in thecirculating coolant. The filter medium effectively removes solidparticles from the circulating coolant. After a period of time, theSCA/filter combination is replaced with a new SCA/filter combination andthis is continued on a periodic basis. Of course, after a certaininterval of time, the coolant itself is replaced.

The present slurries can also be used for addition directly into thecirculating coolant, e.g., in much the same way as operators, such astruck drivers, periodically add additive solutions to circulatingcoolants. However, the present slurries find their greatest and mostadvantageous application in the manufacture of SCA/filter combinations.

The following examples illustrate certain embodiments of the presentinvention and are not to be construed to limit the scope of theinvention.

EXAMPLES 1 TO 24

A series of liquid-solid slurries was prepared from the followingcomponents:

    ______________________________________                                        Component      Description                                                    ______________________________________                                        A              An SCA in powdered form                                                       having a composition similar                                                  to DCA-IV, a SCA sold                                                         commercially by Fleetguard,                                                   Inc. and included in coolant                                                  SCA/filter combinations sold                                                  by Fleetguard, Inc. This                                                      powder is substantially                                                       free of uncombined (liquid)                                                   water.                                                         B              Ethylene glycol                                                C              Suspension Agent                                               D              A liquid corrosion                                                            inhibitor proprietary to                                                      Fleetguard, Inc.                                               E              Liquid water                                                   ______________________________________                                    

Each of the slurries were produced by combining the liquids and thenslowly adding the solid materials with continuous mechanical mixing.These slurries had the following compositions.

    ______________________________________                                                 COMPONENT, WT %                                                      EXAMPLE    A          B      C       D   E                                    ______________________________________                                         1         76         24                                                       2         75         25                                                       3         74         26                                                       4         73         27                                                       5         77         23                                                       6         73         26     1                                                 7         74         25     1                                                 8         71         28     1                                                 9         73.0       26.5   0.5                                              10         73.25      26.75                                                   11         73.0       25.0   0.5     1.5                                      12         70.5       29.0   0.5                                              13         70.75      29.25                                                   14         70.75      28.25          1                                        15         69.5       30.0   0.5                                              16         69.5       30.5                                                    17         68.5       31     0.5                                              18         67.5       32     0.5                                              19         66.5       33     0.5                                              20         65.5       34     0.5                                              21         64.5       35     0.5                                              22         67         27             1    5                                   23         67         22             1   10                                   24         67         17             1   15                                   ______________________________________                                    

Each of these slurries was exposed to ambient conditions, with noadditional mechanical mxiing, for a period of time and observed. Asummary of such observations is as follows:

Examples 1 to 8--The slurries expanded slightly overnight, possibly dueto gassing. Component C appeared to help initially suspend the solids inthe liquid, but did not cause solidification of the slurry overnight.Component C also helped to prevent migration of ingredients overnightand aided in keeping a uniform texture from top to bottom of theslurries. Each of the slurries did get thicker overnight. Slurry 6 hadgood softness and uniformity after about 16 hours. After about 9 daysexposure, Slurries 1, 2, 3, 6, and 7 had become hard or stiff so that,for practical purposes, the slurry would not flow. Slurry 8 was softer,but flowed slowly.

After about 5 days exposure, observations on Slurries 9 to 21 were asfollows. Slurries 9, 10, 11, and 12 were stiff or very stiff andexhibited low flow characteristics. Slurry 17 was moderately stiff.Slurries 13, 14, 15, 16, and 18 each had good body and exhibited goodflow characteristics. Slurries 19, 20, and 21 were very liquid with somephase separation apparent.

After about 9 days exposure, observations on Slurries 9 to 21 were asfollows. Slurries 9, 10, and 12 were very moist to the touch andexhibited low or slow flow characteristics. Slurry 11 was stiff.Slurries 13, 14, and 15 were very moist to the touch and exhibitedmoderate to good flow characteristics. Slurry 13 had some nonuniformityor migration of the solid particles. Slurries 16 to 21 exhibited good tovery good flow characteristics, but some non-uniformity, e.g., particlemigration, phase separation and/or lumpiness, was apparent in each ofthese slurries, possibly due to non-uniform solid particles.

These results and observations indicate that a liquid/solid slurrycontaining SCA with a useful shelf life can be prepared. Someexperimentation may be useful in choosing the relative amounts of liquidand solid and the particle size of the solid depending, for example, onthe specific liquid and solids to be included in the slurry and thedesired shelf life of the slurry. Further, it should be noted that thebody and flow properties of the slurry can be restored at least to someextent by periodic mixing, e.g., at the filter manufacturer's location.However, it is preferred that the slurry have sufficient stability sothat substantially no mixing is required from the time the slurry isprepared to the time it is introduced into the filter.

Slurries 22, 23, and 24 were prepared and observed to determine theeffect of liquid water on the slurry. Slurry 22, as prepared, ws lumpyand some migration of particles was apparent. Slurry 23 and 24 showedprogressively less lumps but more severe separation. The observationsindicate that the presence of liquid water appears to be detrimental tothe stability of the slurry.

EXAMPLE 25

Another slurry was prepared as described above containing 67% by weightof Component A; 32% by weight of Component B and 1% by weight ofComponent D. After 4 days of exposure to ambient temperature, thisslurry exhibited very good flow characteristics with a low degree ofparticle migration. This slurry is useful in manufacturing filter/SCAcombinations. If the solids are milled prior to the slurry beingprepared to obtain more uniform particle size, more solids, relative toliquid, can be added to the slurry. Since this is often advantageous, itis preferred to subject the solids to processing, more preferably priorto the formation of the liquid-solid slurry, effective to provide moreuniformly sized solid particles, i.e., relative to the solid particlesprior to such processing.

EXAMPLES 26 TO 30

A further series of slurries was prepared as described above, exceptthat the solid particles were milled and recovered so that the solidparticles used in the slurry had a more uniform size distributionrelative to the unmilled solid particles. The composition of each of theslurries was as follows:

    ______________________________________                                                 COMPONENT, WT %                                                      EXAMPLE    A         B     C       D   E                                      ______________________________________                                        26         70        29            1                                          27         71        28            1                                          28         72        27            1                                          29         73        26            1                                          30         74        25            1                                          ______________________________________                                    

Each of these slurries exhibited sufficient stability, shelve life andflow characteristics to be useful in the manufacture of filter/SCAcombinations.

EXAMPLES 31 TO 35

Each of the slurries identified in Examples 26 to 30 is shipped in bulkto a manufacturer of conventional filter/SCA combinations. Within twoweeks, each of these slurries is introduced into variously sized filtersusing automatic injection equipment effective to dispense a presetamount of slurry into each filter. No human at the filter manufacturer'slocation needs to come in direct contact with the slurry, and nosubstantial mixing of the slurry by the filter manufacturer is required.These filter/SCA combinations are placed in use in fluid communicationwith circulating coolants in appropriately and differently sizedvehicular diesel engines. These filter/SCA combinations are effective toprovide SCA to the circulating coolants and to filter solid particlesfrom the circulating coolant.

While this invention has been disclosed with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and can be variously practiced within the scope ofthe following claims.

The embodiments of the present invention in which an exclusive propertyor privilege is claimed are as follows:
 1. In a method for manufacturinga circulating coolant system filter which includes assembling a filtermedium, a filter canister into which a supplemental coolant additive isplaced to provide said supplemental coolant additive to the circulatingcoolant and means for placing said supplemental coolant additive in saidfilter canister in fluid communication with the circulating coolant, theimprovement comprising: automatically introducing said supplementalcoolant additive into said filter canister in the form of aliquid-powdered solids slurry.
 2. The method of claim 1 wherein saidsupplemental coolant additive includes at least one corrosion inhibitor.3. The method of claim 2 wherein at least one corrosion inhibitor ispresent in each of the liquid and powdered solids of said slurry.
 4. Themethod of claim 1 wherein said slurry is substantially uniform.
 5. Themethod of claim 1 wherein at least one active component of saidsupplemental coolant additive is present in each of the liquid and thepowdered solids of said slurry.
 6. The method of claim 1 wherein saidslurry contains less than about 50% by weight of liquid and more thanabout 50% by weight of powdered solids.
 7. The method of claim 1 whereinsaid slurry contains about 5% to about 40% by weight of liquid and about60% to about 95% by weight of powdered solids.
 8. The method of claim 1wherein said slurry is substantially dispersible or soluble in saidcirculating coolant.
 9. The method of claim 1 wherein said slurryincludes less than about 15% by weight of liquid water.
 10. The methodof claim 1 wherein said slurry includes less than about 5% by weight ofliquid water.
 11. The method of claim 1 wherein said slurry issubstantially non-aqueous.
 12. The method of claim 1 wherein the majoramount of the liquid in said slurry is ethylene glycol.
 13. The methodof claim 1 wherein said circulating coolant includes both water andethylene glycol.
 14. The method of claim 1 wherein a major amount byweight of said powdered solids in said slurry have diameters of lessthan about 500 microns.
 15. The method of claim 1 wherein substantiallyall of said powdered solids in said slurry have diameters of less thanabout 250 microns.